The fact that only variants of the invention, e.g. one of a number of embodiments of it, are not capable of being performed does not immediately give rise to the conclusion that the subject-matter of the invention as a whole is incapable of being performed, i.e. is incapable of resolving the problem involved and therefore of achieving the desired technical result.
Those parts of the description relating to the variants of the invention which are incapable of being performed and the relevant claims must, however, then be deleted or marked background information that is not part of the invention (see F‑IV, 4.3(iii)) at the request of the division if the deficiency is not remedied. The specification must then be so worded that the remaining claims are supported by the description and do not relate to embodiments which have proved to be incapable of being performed.
In some particular cases (for example claims relating to a combination of ranges or Markush claims), the scope of the claim might encompass a large number of alternatives, some of which correspond to non-working embodiments. In such cases, the presence of non-working embodiments in the claim is of no harm, provided that the specification contains sufficient information on the relevant criteria to identify the working embodiments within the claimed alternatives (G 1/03). See also G‑VII, 5.2.